Protein adsorption and stability of poly(ethylene oxide)-modified surfaces having hydrophobic layer between substrate and polymer

The materials covered with poly(ethylene oxide) (PEO) are of use in a wide variety of biomaterials due to blood compatibility of this polymer. The long-term sustainability of its blood compatibility strongly depends on the stability of the PEO layer against aqueous environment. An attempt was made in the present work to immobilize a PEO layer on the silicon surfaces using a silane coupling agent with the aim to improve the waterproof durability of the layer. Several kinds of PEO-modified substrates having a densely and closely packed hydrocarbon layer between substrate and PEO layer were prepared and the stability of the PEO layer against phosphate buffer saline (pH 7.4) was examined in terms of the density of hydrocarbon chains. Those substrates which have a dense hydrophobic chain layer showed a high waterproof durability and a good ability to suppress protein adsorption.